BAGHDAD, Iraq (CNN) -- A mortar attack Saturday on an Iraqi voter registration site north of Baghdad killed an Iraqi civilian and wounded eight others, a U.S. Army spokesman said.

Four mortar rounds slammed into the site -- which was in a youth center in Dujay, a town between the north-central cities of Tikrit and Samarra, said the spokesman with the Army's 1st Infantry Division.

Iraqi national guardsmen evacuated the injured to a nearby hospital.

Insurgent attacks in Iraq have prompted calls from many Iraqis to delay national elections, scheduled for January 30. Iraq's interim government and the United States appear determined to leave the date unchanged.

There has been concern about the ability to hold elections in parts of the Sunni Muslim heartland, where insurgent attacks have been significant.

Voters will choose a 275-member transitional national assembly. That body will put together a permanent constitution that will go before voters in a referendum. If the law is approved, there will be elections for a permanent government by the end of next year. Interim Iraqi Prime Minister Ayad Allawi has announced he will vie for an assembly seat.

Saturday's attack on the voter registration site followed violence in three northern cities -- Mosul, Kirkuk and Beiji.

In Mosul, a student was killed and six others wounded when a roadside bomb exploded by a passing school bus, Task Force Olympia said in a statement. One insurgent was killed when American-led multinational troops in a patrol -- the blast's intended target -- fired on the attackers.

Task Force Olympia, which includes members of the U.S. Army and Marines and Australian soldiers, is the command and control element for coalition forces in the two northern governorates of Iraq -- Ninevah and Dahuk.

Two attacks on police stations in the city were repelled, the statement said.

In eastern Mosul, Iraqi national guardsmen used a tip from a resident to find a dump truck filled with explosives, Task Force Olympia said.

In Kirkuk, a woman was killed and two other women were wounded overnight when a car attempted to run a U.S. checkpoint in the eastern part of the city, said Gen. Tourhan Yousif, Kirkuk's police chief. No other details were available. Kirkuk has been under an overnight curfew for three months.

An insurgent ambush near Beiji injured four U.S. civilian contractors, a 1st Infantry Division spokesman said. The contractors -- employed by a firm named Cochise -- were on a security patrol when a car bomb detonated near their vehicle, the spokesman said.

Other developments

An investigative hearing has been held for two prominent members of Saddam Hussein's deposed regime: Ali Hassan al-Majid -- also known as "Chemical Ali" for his alleged role in the gassing of Kurds in the late '80s -- and Sultan Hashem Ahmed, Saddam's former defense minister, an investigative magistrate said Saturday. Raad al-Juhyi, head of a panel of investigative judges, said the hearing was not part of upcoming trials for the former regime that were announced this week. (Full story)

Attackers shot and killed the daughter of a former Iraqi president and her husband in their Baghdad home Tuesday, police said Saturday. Sana Abdul Salam Arif was the daughter of Abdul Salam Arif, who was president from 1963 to 1966. Her 22-year-old son, Rafal, was kidnapped, police said.

In a raid Saturday in western Samarra, American soldiers detained three people and confiscated bomb-making materials, binoculars and a bag of black powder, the U.S. military said. Soldiers detained four people in another raid Saturday near Ad Dwar.

The U.S. Embassy has confirmed the identity of an American contractor kidnapped November 1 in Baghdad as Roy Hallums. Hallums was abducted with others after a gunbattle in al-Mansour, the same neighborhood where Briton Kenneth Bigley and Americans Eugene "Jack" Armstrong and Jack Hensley were kidnapped in September. They later were killed.